Field
The present disclosure relates generally to communication systems, and more particularly, to mechanism for avoiding mobility ping pong between a source radio access technology (RAT) and a target RAT during a redirection procedure.
Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
During source-to-target inter-radio access technology (IRAT) redirection, if a user equipment (UE) that is camped on a source RAT is unable to camp on a target frequency of a target RAT (e.g., due to the target frequency of the target RAT being barred or a forbidden timing advance (TA)), the UE may later attempt to reselect or redirect to the same target frequency of the target RAT. The UE may attempt to reselect (in idle mode) or redirect (in connected mode) to the same target frequency of the target RAT because the UE and/or the network may be unaware of the reason for the source-to-target IRAT redirection failure. The redirection failure may lead to a mobility ping pong between the source RAT and the target RAT that causes a negative user experience. There is a need able to enable a UE to avoid ping pong mobility when a redirection procedure from a source RAT to a target RAT fails.